Role of reactive oxygen species during hypertension in response to chronic antiangiogenic factor (sFlt-1) excess in pregnant rats

Growth Restriction in Preeclampsia: Lessons from Animal Models

Preeclampsia remains a major health concern for mother and child. Yet, treatment options remain limited to early delivery. Placental dysfunction in preeclampsia occurs in response to an increase in oxidative stress and inflammatory cytokines with vasoactive and anti-angiogenic factors contributing to impaired maternal and fetal health. Moreover, recent studies indicate a potential role for epigenetic mediators in the pathophysiology of placental ischemia. Numerous animal models are utilized to explore the pathogenesis of preeclampsia and fetal growth restriction. This review provides a brief overview of recent progress in preclinical studies regarding potential therapeutic targets for the treatment and prevention of preeclampsia with an emphasis on fetal growth restriction and the fetal programming of increased cardiovascular risk.

Pathophysiology of Preeclampsia and L-Arginine/L-Citrulline Supplementation as a Potential Strategy to Improve Birth Outcomes

In preeclampsia, the shallow invasion of cytotrophoblast cells to uterine spiral arteries, leading to a reduction in placental blood flow, is associated with an imbalance of proangiogenic/antiangiogenic factors to impaired nitric oxide (NO) production. Proangiogenic factors, such as vascular endothelial growth factor (VEGF) and placental growth factor (PlGF), require NO to induce angiogenesis through antioxidant regulation mechanisms. At the same time, there are increases in antiangiogenic factors in preeclampsia, such as soluble fms-like tyrosine kinase type 1 receptor (sFIt1) and toll-like receptor 9 (TLR9), which are mechanism derivates in the reduction of NO bioavailability and oxidative stress in placenta.Different strategies have been proposed to prevent or alleviate the detrimental effects of preeclampsia. However, the only intervention to avoid the severe consequences of the disease is the interruption of pregnancy. In this scenario, different approaches have been analysed to treat preeclamptic pregnant women safely. The supplementation with amino acids is one of them, especially those associated with NO synthesis. In this review, we discuss emerging concepts in the pathogenesis of preeclampsia to highlight L-arginine and L-citrulline supplementation as potential strategies to improve birth outcomes. Clinical and experimental data concerning L-arginine and L-citrulline supplementation have shown benefits in improving NO availability in the placenta and uterine-placental circulation, prolonging pregnancy in patients with gestational hypertension and decreasing maternal blood pressure.

Oxidative Regulation of Vascular Cav1.2 Channels Triggers Vascular Dysfunction in Hypertension-Related Disorders

Blood pressure is determined by cardiac output and peripheral vascular resistance. The L-type voltage-gated Ca²⁺ (Ca_v1.2) channel in small arteries and arterioles plays an essential role in regulating Ca²⁺ influx, vascular resistance, and blood pressure. Hypertension and preeclampsia are characterized by high blood pressure. In addition, diabetes has a high prevalence of hypertension. The etiology of these disorders remains elusive, involving the complex interplay of environmental and genetic factors. Common to these disorders are oxidative stress and vascular dysfunction. Reactive oxygen species (ROS) derived from NADPH oxidases (NOXs) and mitochondria are primary sources of vascular oxidative stress, whereas dysfunction of the Ca_v1.2 channel confers increased vascular resistance in hypertension. This review will discuss the importance of ROS derived from NOXs and mitochondria in regulating vascular Ca_v1.2 and potential roles of ROS-mediated Ca_v1.2 dysfunction in aberrant vascular function in hypertension, diabetes, and preeclampsia.

Oxidative and Inflammatory Imbalance in Placenta and Kidney of sFlt1-Induced Early-Onset Preeclampsia Rat Model

Preeclampsia (PE) is a pregnancy-specific disorder characterized by the new onset of hypertension plus proteinuria and/or end-organ dysfunction. Here, we investigate the role of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase system as a major component of reactive oxygen species generation, in a rodent model of early-onset preeclampsia induced by excess sFlt1 (soluble fms-like tyrosine kinase 1). Placenta and kidney samples were obtained from normal pregnant and PE rats to measure the sFlt1/PlGF (placental growth factor) ratio in addition to oxidative stress-related parameters, including the activities and expressions of NADPH oxidase isoforms (NOX1, NOX2, and NOX4), components of nitric oxide (NO) metabolism, and antioxidant enzymes. Peroxisome proliferator-activated receptors (PPARα, PPARγ) and cytokines IL1β, IL3, IL6, IL10, and IL18 were also measured to evaluate the inflammation status in our experimental setting. Excessive O₂^●− production was found in rats that were treated with sFlt1; interestingly, this alteration appears to be mediated mainly by NOX2 in the placenta and by NOX4 in the kidney. Altered NO metabolism and antioxidant defense systems, together with mitochondrial dysfunction, were observed in this model of PE. Preeclamptic animals also exhibited overexpression of proinflammatory biomarkers as well as increased collagen deposition. Our results highlight the role of NADPH oxidase in mediating oxidative stress and possibly inflammatory processes in the placenta and kidney of an sFlt1-based model of early-onset preeclampsia.

Animal Models of Preeclampsia: Mechanistic Insights and Promising Therapeutics

Preeclampsia (PE) is a common pregnancy-specific disorder that is a major cause of both maternal and fetal morbidity and mortality. Central to the pathogenesis of PE is the production of antiangiogenic and inflammatory factors by the hypoxic placenta, leading to the downstream manifestations of the disease, including hypertension and end-organ damage. Currently, effective treatments are limited for PE; however, the development of preclinical animal models has helped in the development and evaluation of new therapeutics. In this review, we will summarize some of the more commonly used models of PE and highlight their similarities to the human syndrome, as well as the therapeutics tested in each model.

Progesterone Induced Blocking Factor Reduces Hypertension and Placental Mitochondrial Dysfunction in Response to sFlt-1 during Pregnancy

Preeclampsia (PE) is characterized by new onset hypertension in association with placental ischemia, reduced fetal weight, elevated soluble fms-like tyrosine kinase-1 (sFlt-1), and placental mitochondrial (mt) dysfunction and oxidative stress (ROS). Progesterone induced blocking factor (PIBF) is a product of progesterone signaling that blocks inflammatory processes and we have previously shown PIBF to lower mean arterial blood pressure (MAP) and sFlt-1 in a rat model of PE. Infusion of sFlt-1 causes hypertension and many characteristics of PE in pregnant rodents, however, its role in causing mt dysfunction is unknown. Therefore, we hypothesize that PIBF will improve mt function and MAP in response to elevated sFlt-1 during pregnancy. We tested our hypothesis by infusing sFlt-1 via miniosmotic pumps in normal pregnant (NP) Sprague-Dawley rats (3.7 μg·kg-1·day-1) on gestation days (GD) 13-19 in the presence or absence of PIBF (2.0 µg/mL) injected intraperitoneally on GD 15 and examined mean arterial blood pressure (MAP) and placental mt ROS on GD 19. sFlt-1 increased MAP to 112 + 2 (n = 11) compared to NP rats (98 + 2 mmHg, n = 15, p < 0.05), which was lowered in the presence of sFlt-1 (100 + 1 mmHg, n = 5, p < 0.05). Placental mtATP was reduced in sFlt-1 infused rats versus NP controls, but was improved with PIBF. Placental mtROS was elevated with sFlt-1 compared to NP controls, but was reduced with PIBF. Sera from NP + sFlt-1 increased endothelial cell mtROS, which was attenuated with PIBF. These data demonstrate sFlt-1 induced HTN during pregnancy reduces placental mt function. Importantly, PIBF improved placental mt function and HTN, indicating the efficacy of improved progesterone signaling as potential therapeutics for PE.

Placental mitochondrial function as a driver of angiogenesis and placental dysfunction

The placenta is a highly vascularized and complex foetal organ that performs various tasks, crucial to a healthy pregnancy. Its dysfunction leads to complications such as stillbirth, preeclampsia, and intrauterine growth restriction. The specific cause of placental dysfunction remains unknown. Recently, the role of mitochondrial function and mitochondrial adaptations in the context of angiogenesis and placental dysfunction is getting more attention. The required energy for placental remodelling, nutrient transport, hormone synthesis, and the reactive oxygen species leads to oxidative stress, stemming from mitochondria. Mitochondria adapt to environmental changes and have been shown to adjust their oxygen and nutrient use to best support placental angiogenesis and foetal development. Angiogenesis is the process by which blood vessels form and is essential for the delivery of nutrients to the body. This process is regulated by different factors, pro-angiogenic factors and anti-angiogenic factors, such as sFlt-1. Increased circulating sFlt-1 levels have been linked to different preeclamptic phenotypes. One of many effects of increased sFlt-1 levels, is the dysregulation of mitochondrial function. This review covers mitochondrial adaptations during placentation, the importance of the anti-angiogenic factor sFlt-1in placental dysfunction and its role in the dysregulation of mitochondrial function.

Hypoxia and Mitochondrial Dysfunction in Pregnancy Complications

Hypoxia is a common and severe stress to an organism's homeostatic mechanisms, and hypoxia during gestation is associated with significantly increased incidence of maternal complications of preeclampsia, adversely impacting on the fetal development and subsequent risk for cardiovascular and metabolic disease. Human and animal studies have revealed a causative role of increased uterine vascular resistance and placental hypoxia in preeclampsia and fetal/intrauterine growth restriction (FGR/IUGR) associated with gestational hypoxia. Gestational hypoxia has a major effect on mitochondria of uteroplacental cells to overproduce reactive oxygen species (ROS), leading to oxidative stress. Excess mitochondrial ROS in turn cause uteroplacental dysfunction by damaging cellular macromolecules, which underlies the pathogenesis of preeclampsia and FGR. In this article, we review the current understanding of hypoxia-induced mitochondrial ROS and their role in placental dysfunction and the pathogenesis of pregnancy complications. In addition, therapeutic approaches selectively targeting mitochondrial ROS in the placental cells are discussed.

Animal Models of Preeclampsia: Causes, Consequences, and Interventions

Preeclampsia is a common pregnancy complication, affecting 2% to 8% of pregnancies worldwide, and is an important cause of both maternal and fetal morbidity and mortality. Importantly, although aspirin and calcium are able to prevent preeclampsia in some women, there is no cure apart from delivery of the placenta and fetus, often necessitating iatrogenic preterm birth. Preclinical models of preeclampsia are widely used to investigate the causes and consequences of preeclampsia and to evaluate safety and efficacy of potential preventative and therapeutic interventions. In this review, we provide a summary of the published preclinical models of preeclampsia that meet human diagnostic criteria, including the development of maternal hypertension, together with new-onset proteinuria, maternal organ dysfunction, and uteroplacental dysfunction. We then discuss evidence from preclinical models for multiple causal factors of preeclampsia, including those implicated in early-onset and late-onset preeclampsia. Next, we discuss the impact of exposure to a preeclampsia-like environment for later maternal and progeny health. The presence of long-term impairment, particularly cardiovascular outcomes, in mothers and progeny after an experimentally induced preeclampsia-like pregnancy, implies that later onset or reduced severity of preeclampsia will improve later maternal and progeny health. Finally, we summarize published intervention studies in preclinical models and identify gaps in knowledge that we consider should be targets for future research.

Hydroxychloroquine Mitigates the Production of 8-Isoprostane and Improves Vascular Dysfunction: Implications for Treating Preeclampsia

In preeclampsia, widespread maternal endothelial dysfunction is often secondary to excessive generation of placental-derived anti-angiogenic factors, including soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin (sEng), along with proinflammatory cytokines such as tumour necrosis factor-α (TNF-α) and activin A, understanding of which offers potential opportunities for the development of novel therapies. The antimalarial hydroxychloroquine is an anti-inflammatory drug improving endothelial homeostasis in lupus. It has not been explored as to whether it can improve placental and endothelial function in preeclampsia. In this in vitro study, term placental explants were used to assess the effects of hydroxychloroquine on placental production of sFlt-1, sEng, TNF-α, activin A, and 8-isoprostane after exposure to hypoxic injury or oxidative stress. Similarly, human umbilical vein endothelial cells (HUVECs) were used to assess the effects of hydroxychloroquine on in vitro markers of endothelial dysfunction. Hydroxychloroquine had no effect on the release of sFlt-1, sEng, TNF-α, activin A, or 8-isoprostane from placental explants exposed to hypoxic injury or oxidative stress. However, hydroxychloroquine mitigated TNF-α-induced HUVEC production of 8-isoprostane and Nicotinanamide adenine dinucleotide phosphate (NADPH) oxidase expression. Hydroxychloroquine also mitigated TNF-α and preeclamptic serum-induced HUVEC monolayer permeability and rescued the loss of zona occludens protein zona occludens 1 (ZO-1). Although hydroxychloroquine had no apparent effects on trophoblast function, it may be a useful endothelial protectant in women presenting with preeclampsia.

Resveratrol induces SIRT1-Dependent autophagy to prevent H2O2-Induced oxidative stress and apoptosis in HTR8/SVneo cells

INTRODUCTION

Pre-eclampsia (PE) is a serious complication of pregnancy, and the likely pathogenic basis of early onset PE are placental dysfunction and increased oxidative stress. Resveratrol (RES) is a potent antioxidant which has shown beneficial effects in many diseases. The aim of this study was to investigate the protective effects of RES against oxidative stress-induced damage in trophoblasts, and elucidate the potential mechanisms.

METHODS

We established an in vitro model of oxidative stress by exposing the human first-trimester extravillous trophoblast cell line HTR8/SVneo to H₂O₂. The level of oxidative stress was reflected by ROS, MDA and SOD. The viability of cells was determined by the MTS assay. Apoptosis was detected using Annexin V-FITC staining and flow cytometry. Levels of SIRT1(sirtuin 1) and autophagy-related proteins (LC3, Beclin-1, p62) were detected by western blot. Autophagosomes were observed by transmission electron microscopy (TEM).

RESULTS

Pre-treatment with RES significantly ameliorated H₂O₂-induced cytotoxicity, morphological damage, oxidative stress and apoptosis. Mechanistically, RES restored the levels of SIRT1 and autophagy-related proteins including LC3-II, Beclin-1 and p62 that were dysregulated by H₂O₂. Blocking autophagy by 3-methyladenine (3-MA) completely abolished the protective effects of RES, as did knocking down SIRT1.

CONCLUSION

RES may protect human trophoblasts against H₂O₂-induced oxidative stress by activating SIRT1-dependent autophagy, and therefore has therapeutic potential in PE.

Preeclampsia link to gestational hypoxia

Complications of pregnancy remain key drivers of morbidity and mortality, affecting the health of both the mother and her offspring in the short and long term. There is lack of detailed understanding of the pathways involved in the pathology and pathogenesis of compromised pregnancy, as well as a shortfall of effective prognostic, diagnostic and treatment options. In many complications of pregnancy, such as in preeclampsia, there is an increase in uteroplacental vascular resistance. However, the cause and effect relationship between placental dysfunction and adverse outcomes in the mother and her offspring remains uncertain. In this review, we aim to highlight the value of gestational hypoxia-induced complications of pregnancy in elucidating underlying molecular pathways and in assessing candidate therapeutic options for these complex disorders. Chronic maternal hypoxia not only mimics the placental pathology associated with obstetric syndromes like gestational hypertension at morphological, molecular and functional levels, but also recapitulates key symptoms that occur as maternal and fetal clinical manifestations of these pregnancy disorders. We propose that gestational hypoxia provides a useful model to study the inter-relationship between placental dysfunction and adverse outcomes in the mother and her offspring in a wide array of examples of complicated pregnancy, such as in preeclampsia.

Altered Redox State Modulates Endothelial KCa2.3 and KCa3.1 Levels in Normal Pregnancy and Preeclampsia

AIMS

Altered redox state has been related to the development of normal pregnancy (NP) and preeclampsia (PE). Endothelial K_Ca2.3 and K_Ca3.1 (K_Cas) play an important role in vasodilation, and K_Cas levels are affected by oxidative stress. We investigated the mechanisms of oxidative stress-mediated K_Cas expression modulation during NP and PE.

RESULTS

Human uterine microvascular endothelial cells were incubated in serum from normal nonpregnant women (n = 13) and women with NP (n = 24) or PE (n = 15), or in vascular endothelial growth factor (VEGF), oxidized low-density lipoprotein (ox-LDL), progesterone, or estradiol-17β (E₂)-containing medium for 24 h. NP serum elevated H₂O₂ levels via reducing catalase and glutathione peroxidase 1 levels, thereby enhancing K_Cas levels via a H₂O₂/fyn/extracellular signal-regulated kinase (ERK)-mediated pathway. VEGF enhanced H₂O₂ and K_Cas levels and K_Ca3.1 currents. K_Cas were upregulated and K_Cas activation-induced endothelium-dependent relaxation (EDR) was augmented in vessels from pregnant mice and rats. Whereas PE serum, ox-LDL, progesterone, or soluble fms-like tyrosine kinase 1 (sFlt-1) elevated superoxide levels via elevating NADPH oxidase 2 (NOX2) and NOX4 levels and reducing superoxide dismutase (SOD) 1 levels, thereby downregulating K_Cas. sFlt-1 inhibited EDR. PE serum- or progesterone-induced alterations in levels of K_Cas were reversed by polyethylene glycol-SOD, NOX inhibition, or E₂. Innovation and Conclusions: This is the first study of how endothelial K_Cas levels are modulated during NP and PE. K_Cas were upregulated by soluble serum factors such as VEGF via H₂O₂ generation in NP, and were downregulated by serum factors such as progesterone and ox-LDL via superoxide generation in PE, which may contribute to hemodynamic adaptations in NP or to the development of PE.

Attenuation of oxidative stress and hypertension in an animal model of HELLP syndrome

HELLP (hemolysis elevated liver enzyme low platelet) syndrome is associated with hypertension, inflammation, oxidative stress and endothelial activation. The objective of this study was to determine if oxygen scavenging or endothelin A receptor antagonism improved hypertension and oxidative stress. sFlt-1 and sEndoglin were infused via mini-osmotic pump into normal pregnant rats (NP) on gestational day 12 to create HELLP syndrome. On gestational day 18 arterial catheters were inserted and on gestational day 19 mean arterial pressure was analyzed in rats; serum, urine and tissues were collected for molecular analysis. HELLP rats had significantly increased MAP compared to control normal pregnant rats (P < 0.0005). Endothelin A receptor antagonism via ABT-627 and Tempol, superoxide dismutase mimetic, were administered to a subset of normal pregnant and HELLP rats beginning on gestational day 13 and attenuated mean arterial pressure in HELLP rats (P < 0.05; P < 0.005). There were no statistically significant differences in mean arterial pressure between NP+ET_A Receptor or NP+Tempol treated rats and NP rats (P = 0.22). Endothelin A receptor blockade significantly decreased HELLP induced isoprostane excretion (P < 0.0005), placental and hepatic reactive oxygen species (P < 0.05; P < 0.0005) and increased placental total antioxidant capacity (P < 0.005) compared to untreated HELLP rats. Similar results in isoprostane (P < 0.005), hepatic reactive oxygen species (P < 0.05) and placental total antioxidant capacity (P < 0.05) were seen in HELLP rats treated with Tempol or Endothelin A receptor antagonist vs. untreated HELLP rats. These data demonstrated a role for oxidative stress in contributing to the hypertension, placental and liver damage that is seen in HELLP syndrome.

Resveratrol mitigates trophoblast and endothelial dysfunction partly via activation of nuclear factor erythroid 2-related factor-2

INTRODUCTION

Maternal endothelial dysfunction underlying preeclampsia arises from excessive placental release of anti-angiogenic factors, such as soluble fms-like tyrosine kinase-1 (sFlt1), soluble endoglin (sEng) and activin A. Resveratrol, an activator of the nuclear factor erythroid 2-related factor-2 (Nrf2) transcription factor, mediates the gene expression of antioxidant and vasoprotective factors that may counter the endothelial damage imposed by these anti-angiogenic factors. The objective of this study was to assess whether resveratrol could reduce placental oxidative stress and production of anti-angiogenic factors in vitro and/or improve in vitro markers of endothelial dysfunction via Nrf2 activation.

METHOD

We used in vitro term placental explants to assess the effects of resveratrol on placental oxidative stress and production of sFlt1, sEng and activin A. Using human umbilical vein endothelial cells we investigated the effects of resveratrol on markers of in vitro endothelial dysfunction, including the expression of intercellular adhesion molecule 1 (ICAM1), vascular cell adhesion molecule 1 (VCAM1), E-selectin and endothelin-1, and endothelial permeability. To confirm that resveratrol mediated its effects via Nrf2, we examined the impact of resveratrol on the same in vitro markers of endothelial and placental dysfunction following Nrf2 knockdown.

RESULTS

Resveratrol significantly decreased placental oxidative stress and the production of sFlt1 and activin A. Resveratrol significantly mitigated tumor necrosis factor-α stimulated endothelial expression of ICAM1, VCAM1, E-selectin and endothelin-1 and prevented an increase in endothelial monolayer permeability. Nrf2 knockdown abolished some of the protective effects of resveratrol on endothelial cells, but not in primary trophoblast cells.

CONCLUSION

Features of placental and endothelial dysfunction characteristic of preeclampsia are improved by resveratrol in vitro, partially via the modulation of Nrf2.

Identifying immune mechanisms mediating the hypertension during preeclampsia

Preeclampsia (PE) is a pregnancy-associated disorder that affects 5-8% of pregnancies and is a major cause of maternal, fetal, and neonatal morbidity and mortality. Hallmark characteristics of PE are new onset hypertension after 20 wk gestation with or without proteinuria, chronic immune activation, fetal growth restriction, and maternal endothelial dysfunction. However, the pathophysiological mechanisms that lead to the development of PE are poorly understood. Recent data from studies of both clinical and animal models demonstrate an imbalance in the subpopulations of CD4+ T cells and a role for these cells as mediators of inflammation and hypertension during pregnancy. Specifically, it has been proposed that the imbalance between two CD4+ T cell subtypes, regulatory T cells (Tregs) and T-helper 17 cells (Th17s), is involved in the pathophysiology of PE. Studies from our laboratory highlighting how this imbalance contributes to vasoactive factors, endothelial dysfunction, and hypertension during pregnancy will be discussed in this review. Therefore, the purpose of this review is to highlight hypertensive mechanisms stimulated by inflammatory factors in response to placental ischemia, thereby elucidating a role.

Increased risk for the development of preeclampsia in obese pregnancies: weighing in on the mechanisms

Preeclampsia (PE) is a pregnancy-specific disorder typically presenting as new-onset hypertension and proteinuria. While numerous epidemiological studies have demonstrated that obesity increases the risk of PE, the mechanisms have yet to be fully elucidated. Growing evidence from animal and human studies implicate placental ischemia in the etiology of this maternal syndrome. It is thought that placental ischemia is brought about by dysfunctional cytotrophoblast migration and invasion into the uterus and subsequent lack of spiral arteriole widening and placental perfusion. Placental ischemia/hypoxia stimulates the release of soluble placental factors into the maternal circulation where they cause endothelial dysfunction, particularly in the kidney, to elicit the clinical manifestations of PE. The most recognized of these factors are the anti-angiogenic sFlt-1 and pro-inflammatory TNF-α and AT1-AA, which promote endothelial dysfunction by reducing levels of the provasodilator nitric oxide and stimulating production of the potent vasoconstrictor endothelin-1 and reactive oxygen species. We hypothesize that obesity-related metabolic factors increase the risk for developing PE by impacting various stages in the pathogenesis of PE, namely, 1) cytotrophoblast migration and placental ischemia; 2) release of soluble placental factors into the maternal circulation; and 3) maternal endothelial and vascular dysfunction. This review will summarize the current experimental evidence supporting the concept that obesity and metabolic factors like lipids, insulin, glucose, and leptin affect placental function and increase the risk for developing hypertension in pregnancy by reducing placental perfusion; enhancing placental release of soluble factors; and by increasing the sensitivity of the maternal vasculature to placental ischemia-induced soluble factors.

Hypertension in an Animal Model of HELLP Syndrome is Associated With Activation of Endothelin 1

Women with hypertensive forms of pregnancy such as hemolysis-elevated liver enzymes-low platelet syndrome have increased circulating endothelin 1; however, the relationship between hypertension and endothelin 1 has not been studied. Using an animal model, we sought to determine whether there was an increased activation/dysfunction of endothelin 1, the effect of endothelin 1 receptor-A blockade on hypertension and other manifestations of hemolysis, elevated liver enzymes, and low platelets syndrome. On gestational day 12, timed-pregnant rats were infused with soluble fms-like tyrosine kinase 1 (sFlt-1) and soluble endoglin (sEndoglin; 4.7 and 7 µg/kg) via mini-osmotic pumps for 8 days. A subset of rats were treated with receptor-A antagonist (ABT-627, 5mg/kg) for 8 days. Rats with hemolysis-elevated liver enzymes-low platelet syndrome had significantly increased hypertension (P = .0001), circulating endothelin 1 (P = .03), and a significant 3.3- and 7.2-fold increase in preproendothelin messenger RNA (mRNA) expression in the placenta and liver (P = .01 and .04). Urinary protein:creatinine ratio was significantly increased in these animals (P = .0007), and circulating factors from these rats stimulated a significant increase in endothelial cell secretion of endothelin 1 (P = .001) in an in vitro assay. Blockade of the endothelin 1 receptor A significantly decreased hypertension (P = .001), circulating endothelin 1, and interleukin 17 (P = .004 and .003), placental preproendothelin mRNA expression (P = .016), and urinary protein:creatinine ratio (P = .007) in rats with hemolysis-elevated liver enzymes-low platelet syndrome. Blockade of the endothelin 1 receptor A significantly decreased hemolysis (P = .009), liver enzymes (P = .011), and significantly increased platelet levels (P = .03) and decreased circulating CD4+ and CD8+ T lymphocytes (P = .0004 and .0001) in rats infused with sFlt-1 and sEndoglin. These data support the hypothesis that endothelin 1 activation has a critical role in pathophysiology of as hemolysis-elevated liver enzymes-low platelet syndrome.

Maternally sequestered therapeutic polypeptides - a new approach for the management of preeclampsia

The last several decades have seen intensive research into the molecular mechanisms underlying the symptoms of preeclampsia. While the underlying cause of preeclampsia is believed to be defective placental development and resulting placental ischemia, it is only recently that the links between the ischemic placenta and maternal symptomatic manifestation have been elucidated. Several different pathways have been implicated in the development of the disorder; most notably production of the anti-angiogenic protein sFlt-1, induction of auto-immunity and inflammation, and production of reactive oxygen species. While the molecular mechanisms are becoming clearer, translating that knowledge into effective therapeutics has proven elusive. Here we describe a number of peptide based therapies we have developed to target theses pathways, and which are currently being tested in preclinical models. These therapeutics are based on a synthetic polymeric carrier elastin-like polypeptide (ELP), which can be synthesized in various sequences and sizes to stabilize the therapeutic peptide and avoid crossing the placental interface. This prevents fetal exposure and potential developmental effects. The therapeutics designed will target known pathogenic pathways, and the ELP carrier could prove to be a versatile delivery system for administration of a variety of therapeutics during pregnancy.

CD4+ T cells are important mediators of oxidative stress that cause hypertension in response to placental ischemia

Preeclampsia is associated with oxidative stress, which is suspected to play a role in hypertension, placental ischemia, and fetal demise associated with the disease. Various cellular sources of oxidative stress, such as neutrophils, monocytes, and CD4(+) T cells have been suggested as culprits in the pathophysiology of preeclampsia. The objective of this study was to examine a role of circulating and placental CD4(+) T cells in oxidative stress in response to placental ischemia during pregnancy. CD4(+) T cells and oxidative stress were measured in preeclamptic and normal pregnant women, placental ischemic and normal pregnant rats, and normal pregnant recipient rats of placental ischemic CD4(+) T cells. Women with preeclampsia had significantly increased circulating (P=0.02) and placental CD4(+) T cells (P=0.0001); lymphocyte secretion of myeloperoxidase (P=0.004); and placental reactive oxygen species (P=0.0004) when compared with normal pregnant women. CD4(+) T cells from placental ischemic rats cause many facets of preeclampsia when injected into normal pregnant recipient rats on gestational day 13. On gestational day 19, blood pressure increased in normal pregnant recipients of placental ischemic CD4(+) T cells (P=0.002) compared with that in normal pregnant rats. Similar to preeclamptic patients, CD4(+) T cells from placental ischemic rats secreted significantly more myeloperoxidase (P=0.003) and induced oxidative stress in cultured vascular cells (P=0.003) than normal pregnant rat CD4(+)Tcells. Apocynin, a nicotinamide adenine dinucleotide phosphate inhibitor, attenuated hypertension and all oxidative stress markers in placental ischemic and normal pregnant recipient rats of placental ischemic CD4(+)Tcells (P=0.05). These data demonstrate an important role for CD4(+) T cells in mediating another factor, oxidative stress, to cause hypertension during preeclampsia.

TH17- and IL-17- mediated autoantibodies and placental oxidative stress play a role in the pathophysiology of pre-eclampsia

Pre-eclampsia is a multisystem disorder of pregnancy that affects 5-8% of pregnancies. The pathophysiologic mechanisms that lead to the development of pre-eclampsia are poorly understood. Higher than normal levels of circulating TH17 is observed in preeclamptic women compared to women with normal pregnancy. TH17 cells are a subset of CD4+ T helper cells that are characterized by their secretion of IL-17. Recent studies suggest a role for TH17 cells and IL-17 in the pathophysiology of pre-eclampsia. In this review, we will discuss the known function of TH17 cells and IL-17 in immunity and vascular function. We will then review the role of IL-17 and TH17 cells in normal pregnancy and their association with pre-eclampsia, followed by a discussion of the literature to examine a potential role for IL-17 and TH17 cells in mediating pathophysiology in pre-eclampsia.

Heme oxygenase inhibition increases blood pressure in pregnant rats

BACKGROUND

During normal gestation, the placenta is a relatively hypoxic organ and, as such, is subject to significant oxidative stress. In the preeclamptic patient, inadequate remodeling of the maternal vasculature severely exacerbates placental oxidative stress, which has been shown to be an important component of maternal hypertension. There is emerging evidence that Heme Oxygenase-1 (HO-1) acts as an important regulator of placental and cardiovascular function during normal pregnancy. Here, we have examined the effect of Heme Oxygenase (HO) inhibition in late gestation on maternal blood pressure, angiogenic balance, and placental oxidative stress in pregnant rats.

METHODS

HO activity was inhibited with tin mesoporphyrin (SnMP), which was administered on gestational day 14, and blood pressure was measured on gestational day 19. Placental angiogenic balance and plasma Vascular Endothelial Growth Factor (VEGF) were determined by sandwich enzyme-linked immunosorbent assay. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity was measured by lucigenin chemilluminescence.

RESULTS

In response to SnMP treatment, maternal mean arterial pressure (MAP) was significantly increased (99±1 vs. 113±2mm Hg; P < 0.05; n = 15 per group). Placental soluble fms-like tyrosine kinase-1 (sFlt-1) (631±47 vs. 648±26 pg/mg; P = 0.76) levels in the placenta were not affected by HO inhibition. Additionally, there was no significant difference in free VEGF in the maternal circulation (287±22 vs. 329±14 pg/ml; P = 0.11). There was, however, a significant decrease in placental VEGF (23±2 vs. 16±1 pg/mg; P < 0.05) and a significant increase in placental NADPH oxidase activity in SnMP-treated rats (2021±238 vs. 3005±301 RLU/min/mg; P < 0.05).

CONCLUSIONS

Our results demonstrate that HO is an important regulator of blood pressure and an important antioxidant in the developing placenta.

Tumor necrosis factor-alpha, interleukin-6, and interleukin-10 levels are altered in preeclampsia: a systematic review and meta-analysis

PROBLEM

Published reports testing the association between cytokine levels and preeclampsia are conflicting. This comprehensive systematic review and meta-analysis aimed at testing the association between preeclampsia and maternal circulating tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, and IL-10.

METHOD OF STUDY

A systematic literature search of studies reporting maternal circulating TNF-α, IL-6, and IL-10 in women with preeclampsia and normotensive pregnant women was conducted yielding 41, 28, and 12 eligible reports, respectively.

RESULTS

Both mild preeclampsia and severe preeclampsia were associated with elevated TNF-α [mean difference (MD) = 7.34 pg/mL, 95% CI 5.02-9.66 and MD = 7.91 pg/mL, 95% CI 4.72-11.10, respectively] and IL-6 (MD = 61.01 pg/mL, 95% CI 14.24-107.77 and MD = 28.54 pg/mL, 95% CI 15.90-41.17, respectively) in the third trimester. Preeclampsia was also associated with elevated levels of IL-10 (MD = 5.54, 95% CI 0.69-10.38). The systematic review of studies reporting median data was in consensus with the parametric data.

CONCLUSION

This systematic review and meta-analysis with accompanying summary of non-parametric data shows elevated maternal circulating TNF-α, IL-6, and IL-10 levels in preeclampsia.

Seeking the mechanism(s) of action for corticosteroids in HELLP syndrome: SMASH study

INTRODUCTION

Administration of dexamethasone to the hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome patients (10 mg intravenously [IV] every 12 hours) shortens the disease course and reduces maternal morbidity in patients treated at the University of Mississippi Medical Center (UMMC), associated with this severe form of preeclampsia. However, the pathophysiological mechanisms involved with this intervention remain unclear.

OBJECTIVE

We sought to investigate the potential role of IV dexamethasone to restore the imbalance among antiangiogenic and inflammatory factors known to be significantly elevated in women with HELLP syndrome.

STUDY DESIGN

This was a single-center prospective study of women diagnosed with HELLP syndrome who were treated for IV dexamethasone at UMMC. Blood was drawn prior to dexamethasone administration and again 12 and 24 hours after the initial dexamethasone administration. Enzyme-linked immune assays were used to measure circulating inflammatory cytokines and antiangiogenic factors. A repeated-measures analysis of variance was used to analyze the data collected before, after, and during dexamethasone administration.

RESULTS

Seventeen women with HELLP syndrome were enrolled in this study. Dexamethasone significantly decreased evidence of hemolysis (P = .002) and liver enzymes (P = .003), and significantly increased platelets (P = .0001) within 24 hours of administration. Circulating interleukin-6 levels after 24 hours were decreased (P < .001); soluble fms-like tyrosine kinase-1 and soluble endoglin were also significantly decreased by 24 hours after dexamethasone administration (P < .002 and P < .004, respectively). There were no significant differences in circulating levels of placental growth factor (P = .886) due to dexamethasone administration. Angiotensin II receptor autoantibody levels were unchanged by dexamethasone administration.

CONCLUSION

We conclude that 1 important mechanism of dexamethasone administration is to blunt the release of both antiangiogenic and inflammatory factors suggested to play role in the pathophysiology of HELLP syndrome.

Effects of shear stresses and antioxidant concentrations on the production of reactive oxygen species in lung cancer cells

Reactive oxygen species (ROS) are known to be a key factor in the development of cancer, and many exogenous sources are supposed to be related to the formation of ROS. In this paper, a microfluidic chip was developed for studying the production of ROS in lung cancer cells under different chemical and physical stimuli. This chip has two unique features: (1) five relative concentrations of 0, 1/8, 1/2, 7/8, and 1 are achieved in the culture regions; (2) a shear stress gradient is produced inside each of the five culture areas. Lung cancer cells were seeded inside this biocompatible chip for investigating their response to different concentrations of H2O2, a chemical stimulus known to increase the production of ROS. Then the effect of shear stress, a physical stimulus, on lung cancer cells was examined, showing that the production of ROS was increased in response to a larger shear stress. Finally, two antioxidants, α-tocopherol and ferulic acid, were used to study their effects on reducing ROS. It was found that high-dose α-tocopherol was not able to effectively eliminate the ROS produced inside cells. This counter effect was not observed in cells cultured in a traditional chamber slide, where no shear stress was present. This result suggests that the current microfluidic chip provides an in vitro platform best mimicking the physiological condition where cells are under circulating conditions.

Pathogenesis of pre-eclampsia: marinobufagenin and angiogenic imbalance as biomarkers of the syndrome

Pre-eclampsia (preE), a pregnancy disorder with the de novo onset of hypertension and proteinuria after 20 weeks of gestation, has multiple triggers that initiate pathophysiologic mechanisms. This review addresses translational aspects of preE by synthesizing information on preE pathogenesis, describing diagnostic biomarkers that predict disease, and suggesting strategies to lessen adverse outcomes. Key to this understanding is the role of cardiotonic bufodienolides, with marinobufagenin (MBG) as the prototype, and angiogenic factors in preE pathogenesis. Data from a rat model believed to mimic human preE show that urinary excretion of MBG increases before the onset of hypertension and proteinuria and that affected animals have an increased vascular leakage and blood brain barrier permeability. Angiogenic imbalance occurs with the onset of the syndrome in this model. Also, we report that MBG levels in preE patients exceed those in normal pregnancy and that angiogenic factors are altered in patients showing signs and symptoms of overt disease. In vitro administration of MBG inhibits cytotrophoblast function and triggers hyperpermeability in endothelial cell monolayers. We advance the hypotheses that MBG precedes preE; MBG causes disruption of tight junction proteins leading to vascular leak via activation of MAPK which triggers apoptotic mechanisms resulting in further endothelial dysfunction leading to edema with the release of angiogenic factors. This review provides new evidence about the role of MBG and vasoactive intermediates in preE pathogenesis including the neurologic sequela and may reveal new therapeutic targets for the prevention of preE complications.

Mechanisms and management of hypertension in pregnant women

Hypertension is the most common medical disorder encountered during pregnancy. A recent report highlighted hypertensive disorders as one of the major causes of pregnancy-related maternal deaths in the United States. Significant advances in our understanding of preeclampsia, a form of hypertension unique to pregnancy, have occurred in recent years. The optimal timing and choice of therapy for hypertensive pregnancy disorders involves carefully weighing the risk-versus-benefit ratio for each individual patient, with an overall goal of improving maternal and fetal outcomes. In this review, we summarize the mechanisms thought to be involved, review the current management guidelines for hypertensive pregnancy disorders as recommended by international guideline groups, and outline some newer perspectives on management.

Hypertension in response to AT1-AA: role of reactive oxygen species in pregnancy-induced hypertension

BACKGROUND

Agonistic autoantibodies to the angiotensin II type I receptor (AT1-AA) and reactive oxygen species (ROS) are implicated in the pathophysiology of preeclampsia. The objective of this study was to determine the role of AT1-AA to stimulate placental oxidative stress in vivo and role ROS in mediating hypertension in response to AT1-AA during pregnancy.

METHODS

To achieve these goals, blood pressure (mean arterial pressure (MAP)) and ROS were analyzed in AT1-AA-induced hypertensive pregnant rats in the presence and absence of a superoxide dismutase mimetic, tempol. Rat AT1-AA (1:50) and tempol (30 mg/kg/day) were administered to pregnant rats beginning on day 12 of gestation. On day 19, MAP was analyzed and tissues collected for ROS analysis via lucigenin chemiluminescence.

RESULTS

MAP increased from 101 ± 2 normal pregnant (NP) rats to 116 ± 2 mm Hg in chronic AT1-AA infused rats (P = 0.002). Placental basal and NADPH oxidase stimulated ROS was 29 ± 6 and 92 ± 10 relative light units (RLUs) in NP rats. These levels increased to 159 ± 29 (P < 0.0001) and 287 ± 60 RLUs (P < 0.006) in AT1-AA infused rats. MAP in AT1-AA + tempol rats was 109 ± 2 mm Hg, no difference than tempol-treated controls (109 ± 3 mm Hg). Administration of tempol decreased basal and NADPH-stimulated placental ROS in AT1-AA-treated rats (121 ± 13; 262 ± 21 RLUs). Basal and NADPH-stimulated ROS in tempol-treated controls were 69 ± 24; 141 ± 33 RLUs.

CONCLUSION

This study indicates that AT1-AA's contribute to placental oxidative stress; one mechanism whereby the AT1-AA mediates hypertension during pregnancy.